In general, an aquifer is a naturally-occurring, underground layer (or layers) of water-bearing permeable rock or unconsolidated material (e.g., gravel, sand, silt or clay).
A water well is an artificial excavation used for the purposes of withdrawing water from an underground aquifer. Water may be drawn from a well using, for example, an electric or mechanical pump. Wells can vary greatly in depth, water volume and water quality.
In certain implementations, substantial amounts of water may be removed from a well for drinking, heating, cooling, irrigation and other uses.